Electric circuit breaker



March 30, 1937 w PAUL 2,075,748

ELECTRIC CIRCUIT BREAKER Filed Aug. 1, 1935 Inventor: William E. Paul,

Patented Mar. 30, 1937 UNITED STATES ELECTRIC CIRCUIT BREAKER William E.Paul, Schenectady, N. Y., assignor to General Electric Company, acorporation of New York Application August 1, 1935, Serial No. 34,178

8 Claims.

My invention relates to electric circuit breakers, more particularly toelectric circuit breakers of the oil-blast type for use in atransmission line which is controlled by time delay relays, such asrelays of the well known inverse time limit type.

It is customary to control the circuit breakers in a high voltage powertransmission line by means of time delay relays which function to delaytripping of the breaker a few cycles in re- 10 sponse to comparativelylight overloads, but which act quickly to trip the breaker on heavyoverloads or short circuits. Circuit breakers of the well knownoil-blast type have heretofore been used in high voltage transmissionlines, the

operation of such breakers generally depending on a tripping operationinitiated by the current responsive relay. When the breaker is tripped,separation of the contact structure causes an initial ,orpressure-generating arc and a second or.

main arc in series therewith which is extinguished by a blast of liquiddirected by the pressure-generating arc. Accordingly, it will be notedthat in systems as above described formation of the pressure-generatingarc is dependent on the conventional breaker tripping operation.

In accordance with my invention; the pressuregenerating arc is formedindependently of the relay operation or tripping of the breaker and incase of appreciable time delay in the tripping operation is formed priorto the actual tripping of the breaker so that adequate pressure isimmediatelyavailable for interrupting the main arc.

My invention will be more fully setforth in the following descriptionreferring to the accompanying drawing, and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and forming a part of this specification.

Referring to the drawing, Fig. 1 is a diagram- 0' maticillustratio'n ofa single phase of a high voltage transmission line in which my inventionis incorporated and Fig. 2 is an elevational view,

partly in section, of, a circuit breaker of the oilblast type embodyingmy invention.

Referring more particularly to Fig. 1, a single phase power circuitindicated at I is controlled by a circuit breaker 2 operativelyrelated-to a tripping latch 3 and being illustrated by way of example.

The breaker, which is normally biased towards time delay relay 4, arelay of the inverse time limit type, well known in the art,

to close the circuit of the strip coil 8 through the contacts at 9.Subsequent release of the latch at 3 permits the breaker to open underthe influence of suitable bias. An auxiliary switch is indicated at II)for opening the trip coil circuit after the breaker is opened, therebypermitting resetting of the latch at 3.

The circuit breaker 2, which is preferably of the well known oil-blasttype, comprises a movable bridging member Il, each end of which coactswith a relatively movable intermediate contact I2 andpressure-generating contact l3. In the closed circuit positionillustrated, the contacts of each pole are in abutting engagement, thecircuit being completed through the bridging member I I. In a well knownform, the contact structure is arranged so that opening movement of thebridging member I I first causes separation of the contacts I2 and I3 toform the pressure-generating arc and subsequently causes separation ofthe contacts I I and I2 .to form the main arc which is subjected to theoil blast.

For the purpose of initiating formation of the pressure-generating arcindependently of the tripping operation, each contact I3, which iscomposed of magnetic material, is electrically connected and operativelyrelated to a coil I4 which when sufiiciently energized draws the contactI3 away from contact I2 to form the pressure-generating arc.Accordingly, notwithstanding a delayed action of the relay 4 in trippingthe breaker the electro-magnetic means at I4 would cause, in response topredetermined current, movement of the contacts l3 to form thepressure-generating arc.

In circuit breakers of the oil-blast type this feature is particularlydesirable since adequate pressures are generated at heavy currents butat lower currents a stronger oil blast is often-desired for quick andpositive interruption of the arc. By building up pressure before theinyerse timelimit relays operate at low currents to trip the breaker, astrong, positive oil blast is assured.

Referring more particularly to Fig. 2 which illustrate's the structuraldetails of an oil-blast circuit breaker adapted for the system abovedescribed, the circuit at I is completed by the bridging member I I andby relatively movable contact structure within an explosion pot I5. Theexplosion pot, which is composed of a suitable mechanically stronginsulating material, issupported by an adapter l6 which is in turnmounted at the lower end of the lead-in conductor insulating bushing-I1.The structure above described is immersed in a suitable arcextinguishing liquid such as oil, the level of which is indicated at it.

The breaker which is illustrated in the closed circuit positioncomprises an electromagnetic device l9 mounted at the upper part of theexplosion chamber for controlling the pressuregenerating contact la. Thedevice l9 comprises the coil M, which is electrically connected at oneterminal to the lead-in conductor at 2d and at the other terminal to thecontact l3, and a magnetic core 2!! within which the contact id is drawnagainst the bias of spring 22 upon predetermined fiow of current throughthe coil M.

The intermediate contact i2 is suitably supported in the top of theexplosion chamber by an insu ating plate 23 and supports 24 and isbiased by spring 25 into engagement with the tubular contact 26 carriedby the bridging member l t.

For the purpose of facilitating acceleration of the oil blast, theintermediate contact it is provided with a passage 2i communicatingdirectly with the interiors of the explosion pot it and the tubularcontact 2 respectively. This feature per se is disclosed and claimed inmy copending application (S. N. 34,179) filed concurrently herewith andassigned to the same assignee as the present invention.

The operation of the circuit breaker illustrated at Fig. 2 is believedto be apparent from the foregoing description. In response topredetermined current, which. may be insufficient to cause instantaneousoperation of the relay, the contact i3 is drawn by the coil E l awayfrom the contact 32, thereby forming within the explosion pot an initialpressure generating are. Subsequent tripping of the breaker causes thetubular contact 26 to move downwards followed for a short distance theintermediate contact under the bias of spring 25. At the throat lid ofthe explosion pot separation of the contacts l2 and 26 takes place toterm the main arc which is immediately subjected to an oil blast fromthe pot under the influence of the pressure generated therein.

The instant application of the oil blast is not only effective toshorten the duration of arcing and therefore the arc length, but alsothe predetermined building up of pressure assures positive andconsistent interruption of the circuit at light currents. In the case ofheavy currents, the pressure is not unduly increased by the in stantformation of the pressure-generating arc since in such a case the relayalso acts practically instantaneously to trip the breaker.

It will be noted that the passage directly connecting the interiorsrespectively of the e plosion pot and movable tubular contact permitsthe oil blast to be under Way in response to the pressure-generating areat the time the breaker is tripped, thereby further speeding up theapplication of the oil blast. passage likewise relieves excessivepressure within the explosion pot.

It should be understood that my invention is not limited to specificdetails of construction and arrangement thereof herein illustrated, andthat changes and modifications may occur to one skilled in the artwithout departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. An electric circuit breaker of the oil-blast type comprising anarc-extinguishing liquid, circuit interrupting structure immersed insaid liq- The aforesaid acvaves uid including means forming a pressuregenerating arc, means forming a main arc, means utilizing the pressureof said first are for directing liquid through said main arc, and meansresponsive to predetermined current through said breaker for controllingformation of said pressure generating arc prior to the main circuitopening movement of said breaker.

2. An electric circuit breaker of the oil-blast type comprising anarc-extinguishing liquid, separable contact structure immersed in saidliquid arranged to form a pressure generating arc and a main arcincluding a movable contact member for causing formation of saidmainarc, means utilizing the pressure of said first are for directing liquidthrough said main arc, and means responsive to current through saidbreaker for causing formation of said pressure generating areindependently of said movable contact member.

3. An electric circuit breaker of the oil-blast type comprising anarc-extinguishing liquid, rel-- atively movable contact structureimmersed in said liquid arranged upon circuit opening movement of saidbreaker to form two breaks in series, and electromagnetic meansconnected in the circuit to be interrupted coacting with said contactstructure for causing, in response to predetermined current, formationof one of said breaks independently of said other break= l. An electriccircuit breaker of the oil-blast type comprising an arc-extinguishingliquid, circuit interrupting structure immersed in said liquid includinga relatively fixed contact, an intermediate contact and a movablecontact arranged to form a preliminary pressure generating arc and amain are upon opening movement of said movable contact, andelectromagnetic means coacting with said fixed contact for causing, inresponse to predetermined current, formation of said pressure generatingarc prior to and independently of opening movement of said movablecontact.

5. An electric circuit breaker oi the oil-blast type comprising meansforming a pressure generating arc, means forming a main arc, means fordirecting an arc extinguishing liquid under pressure into said main arc,and means responsive to a predetermined current through said breaker forcausing'tormation of said pressure generating arc prior to andindependently of the contact movement for forming said main are so thatpreliminary acceleration of liquid in the path of said blast is effectedprior to formation of said main arc.

6. An electric circuit breaker of the oil-blast type comprising anexplosion pot, a relatively fixed contact, an intermediate contact and atubular contact coacting in said pot and arranged so as to cause apressure generating arc and a main arc, and electromagnetic meansconnected in the circuit to be interrupted coacting with said fixedcontact for causing in response to predetermined current separation ofsaid fixed and intermediate contacts to cause formation of said pressuregenerating arc independently of said tubular contact, said intermediatecontact hav ing a passage for transmitting pressure from said pot to theinterior of said tubular contact prior to separation of saidintermediate and tubular contacts so that preliminary acceleration ofliquid in said tubular contact is effected in response to pressure insaid pot prior to formation of said main arc.

7. A circuit interrupting system comprising an electric circuit breakerof the oil-blast type in cluding an arc-extinguishing liquid, circuitinterrupting structure immersed in said liquid ar- 5 ranged to form amain are upon tripping of said breaker and a pressure generating are forcausing interruption of said main arc, and a time delay relay responsiveto circuit conditions for causing tripping of said breaker, said breakerin- 10 eluding means responsive to said circuit conditions for formingsaid pressure-generating arc prior to tripping of said breaker.

8. A circuit interrupting system comprising in combination a relay ofthe inverse time limit type and an electric circuit breaker oi the oilblast type, said relay arranged to trip said circuit breaker in.response to and in accordance with predetermined circuit conditions,said circuit breaker comprising relatively movable contact structureimmersed in an arc-extinguishing liquid arranged to form two arcs inseries, the pressure generated in said liquid by one of said arcs beingutilized to cause interruption of the other of said arcs, andelectromagnetic means responsive to the aforesaid circuit conditions forforming the pressure-generating arc prior to tripping of the circuitbreaker by said relay.

WILLIAM E. PAUL.

